Ultrasound diagnosis of occult pneumothorax.

OBJECTIVES: Pneumothorax can be missed by bedside radiography, and computed tomography is the current alternative. We asked whether lung ultrasound could be of any help in this situation. DESIGN: Retrospective study. SETTING: The medical intensive care unit of a university-affiliated teaching hospital. PATIENTS: All patients admitted to the intensive care unit are routinely scanned with whole-body ultrasound (including screening for pneumothorax) and chest radiography. The study population included 200 consecutive undifferentiated intensive care unit patients who received a chest computed tomography scan in addition to ultrasound and chest radiograph. Forty-seven consecutive cases of radioccult pneumothorax were compared with 310 consecutive hemithoraces free from pneumothorax in the intensive care unit. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: Three signs were investigated at the anterolateral chest wall in supine patients: lung sliding, the A line sign, and the lung point. A total of 357 hemithoraces were analyzed in this study, 47 with occult pneumothorax and 310 controls. Four of the 47 cases of pneumothorax were excluded from the final analysis (parietal emphysema) as well as eight of the 310 controls (large dressings), leaving a final study population of 345 hemithoraces in 197 patients. Feasibility was 98%. Ultrasound scans in all 43 examinable patients with pneumothorax showed absent lung sliding, 41 of 43 patients had the A line sign, and 34 exhibited a lung point. Among 302 analyzable controls, 65 had absent lung sliding, 16 of them showed an A line sign, and none showed a lung point. For the diagnosis of occult pneumothorax, the abolition of lung sliding alone had a sensitivity of 100% and a specificity of 78%. Absent lung sliding plus the A line sign had a sensitivity of 95% and a specificity of 94%. The lung point had a sensitivity of 79% and a specificity of 100%. CONCLUSIONS: For the diagnosis of occult pneumothorax, ultrasound can decrease the need for computed tomography.

Ultrasound diagnosis of alveolar consolidation in the critically ill.

OBJECTIVE: Alveolar consolidation is a basic concern in critically ill patients. Radiography is not a precise tool, and referral to CT raises problems (transport, irradiation). The aim of this study was to assess the utility of ultrasound in the diagnosis of alveolar consolidation. DESIGN: Prospective clinical study. SETTING: The medical ICU of a university-affiliated teaching hospital. PATIENTS: A total of 65 cases of alveolar consolidation proven on CT were compared to 53 CT controls. MEASUREMENTS: Alveolar consolidation was defined as a tissue-like pattern visible at the chest wall, arising from the pleural line and devoid of centrifugal inspiratory dynamics. RESULTS: Feasibility was 99%. In 65 cases of alveolar consolidation, ultrasound was positive in 59 and negative in 6. In 52 analyzable controls, ultrasound was negative in 51 and positive in 1. Sensitivity of ultrasound was 90% and specificity 98%. A concordance test showed a Kappa coefficient of 0.89. Among 62 posterior locations on CT, ultrasound showed posterior consolidation patterns in 56 cases and was negative in 6. Ultrasound showed anterior involvement in all 3 cases of whole lung consolidation. CONCLUSIONS: Ultrasound provides a reliable non-invasive, bedside method for accurate detection and location of alveolar consolidation in critically ill patients.

The "lung pulse": an early ultrasound sign of complete atelectasis.

OBJECTIVE: Complete atelectasis can be immediately generated by selective intubation. A dynamic lung ultrasound sign can be described as the association of absent lung sliding with the perception of heart activity at the pleural line, a sign which was called "lung pulse." We examined whether this sign be used promptly to confirm complete atelectasis due to selective intubation. DESIGN AND SETTING: Prospective study in the medical intensive care unit of a university-affiliated teaching hospital. PATIENTS: Consecutive patients with no history of respiratory disorders and needing intubation were enrolled. Fifteen patients with selective intubation of the right lung were compared with 30 patients with nonselective intubation and 15 healthy volunteers. INTERVENTIONS: The "lung pulse" was sought at the left anterolateral chest wall in intubated patients. Healthy subjects were studied during breathing and apnea. RESULTS: A left "lung pulse" was immediately present in 14 of 15 patients with right selective intubation, and absent, with normal lung sliding, in all 30 correctly intubated patients and in all 15 healthy subjects during breathing. All healthy subjects exhibited a "lung pulse" in apnea. The "lung pulse" had a sensitivity of 93% and a specificity of 100% for the diagnosis of complete atelectasis following selective intubation in patients without previous respiratory disorders. CONCLUSIONS: The "lung pulse" is a sign of complete atelectasis which is observable immediately before radiological changes. Its absence which is correlated with the absence of selective intubation and of conserved lung inflation can eliminate the need for confirmation radiography.